Power transmission device for a scooter

ABSTRACT

A power transmission device for a powered scooter is provided. The power transmission device includes a drive shaft, a driven shaft and two or more timing belt transmission device. The timing belt transmission device includes a first sprocket wheel attached on the drive shaft, a second sprocket wheel attached on the driven shaft, and a timing belt wound on the first sprocket wheel and the second sprocket wheel. The ratio of the diameter of the first sprocket wheel and the diameter of the second sprocket wheel is predetermined to provide a desired speed change ratio. The timing belt may be made of rubber or chain.

CLAIMING FOREIGN PRIORITY

[0001] The applicant claims and requests a foreign priority, through the Paris Convention for the Protection of Industry Property, based on a patent application filed in the Republic of Korea (South Korea) with the filing date of Sep. 6, 2001, with the application number UTILITY-2001-0027293, by the applicant (See the Attached Declaration).

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a power transmission device for a small, portable scooter. More particularly, the invention relates to a power transmission device that transmits power from an engine to a drive wheel, and has a drive shaft and a driven shaft.

[0003] A small, powered scooter has become popular as a transportation means for a short distance, and for leisure and sports activities. The powered scooter has a shape of a skateboard and is equipped with a small engine and a power transmission device transmitting the rotational force of the engine to the rear wheel of the scooter. The power transmission device includes a timing chain and sprocket wheels around which the timing chain is wound.

[0004] Since the powered scooter has a very small and simple structure, unlike an automobile or a motorcycle, impacts from the ground is easily transferred to the power transmission device. Also other impact or load such as abrupt or excessive manipulation made the shaft or timing chain of the power transmission device to be damaged or broken easily. Thus, there were a lot of maintenance problems related to the power transmission device causing difficulties for maintenance service of the scooter, and excessive maintenance cost for the consumer.

SUMMARY OF THE INVENTION

[0005] The present invention contrives to solve the problems of the prior art. Therefore, an object of the invention is to provide a rugged power transmission device for a small powered scooter.

[0006] Another object of the invention is to provide a power transmission device that is simple yet sturdy to resist impacts from the ground and from starting and stopping of the scooter.

[0007] Still another object of the invention is to provide a power transmission device that is reliable and has a long service life.

[0008] To achieve the above-described objects, the invention provides a power transmission device for a powered scooter. The power transmission device includes a drive shaft, a driven shaft, and two or more timing belt transmission devices. Each of the timing belt transmission devices includes a first sprocket wheel attached on the drive shaft, a second sprocket wheel attached on the driven shaft, and a timing belt wound on the first sprocket wheel and the second sprocket wheel. The ratio of the diameters of the first sprocket wheel and the diameter of the second sprocket wheel is predetermined to give desired speed reduction.

[0009] The timing belt is made of rubber and has teeth that engage with the teeth of the first and second sprocket wheels. Alternatively, the timing belt is a chain that has a plurality of links that engage with the teeth of the first and second sprocket wheels.

[0010] The power transmission device further includes an automatic clutch connected to the drive shaft. The automatic clutch transmits power of an engine of the powered scooter when the engine rotates above a predetermined rotational speed, and the clutch does not transmit power of the engine when the engine rotates below a predetermined rotational speed.

[0011] The power transmission device also includes a housing that encloses the drive shaft, the driven shaft and the timing belt transmission devices. The housing has recesses and bearings received in the recesses. The drive shaft and the driven shaft are supported by the bearings.

[0012] The advantageous effects of the present invention are numerous in that: (1) the power transmission device is simple and rugged; (2) the power transmission device provides smooth and convenient manipulation of the scooter; and (3) the power transmission is reliable and keeps the maintenance cost of the scooter low.

[0013] Although the present invention is briefly summarized, the fuller understanding of the invention can be obtained by the following drawings, detailed description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] These and other features, aspects and advantages of the present invention will become better understood with reference to the accompanying drawings, wherein:

[0015]FIG. 1 is a schematic, elevational view of a powered scooter;

[0016]FIG. 2 is a top view of the scooter;

[0017]FIG. 3 is an elevational view of a power transmission device;

[0018]FIG. 4 is a cross-sectional view taken along the line 4-4 in FIG. 3;

[0019]FIG. 5 is a schematic view showing a timing belt made of rubber; and

[0020]FIG. 6 is a schematic view showing a timing belt made of a chain.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021]FIGS. 1 and 2 show a small, powered scooter 10. The scooter includes a steering portion 12, a power driving portion 14, and a frame portion 16 connecting the steering portion 12 and the power driving portion 14. The steering portion 12 has a front wheel 18, a steering axis 20, and a foldable handle 22. The power driving portion 14 has an engine 24, a power transmission device 26, and a rear wheel 28 that is driven by the engine 24. The frame portion 16 has a foot board 30, a chair 32, and a frame 34.

[0022]FIGS. 3 and 4 show the power transmission device 26. The power transmission device 26 includes a drive shaft 36, a driven shaft 38, and two or more timing belt transmission devices 40. Each of the timing belt transmission devices 40 includes a first sprocket wheel 42 attached on the drive shaft 36, a second sprocket wheel 44 attached on the driven shaft 38, and a timing belt 46 wound on the first sprocket wheel 42 and the second sprocket wheel 44. The ratio of the diameter of the first sprocket wheel 42 and the diameter of the second sprocket wheel 44 is predetermined to get a desired rotational speed reduction.

[0023] The power transmission device 26 further includes an automatic clutch 48 connected to the drive shaft 36. The automatic clutch 48 transmits the power of the engine 24 when the engine 24 rotates above a predetermined rotational speed, but does not transmit the power of the engine 24 when the engine 24 rotates below a predetermined rotational speed.

[0024] The power transmission device 26 further includes a housing 50 that encloses the drive shaft 36, the driven shaft 38 and the timing belt transmission devices 40. The housing 50 has recesses 52, 54 and bearings 56, 58 received in the recesses 52, 54 in its upper portion. The drive shaft 36 is supported by the bearings 56, 58. The housing 50 also has recesses 60, 62 and bearings 64, 66 received in the recesses 60, 62 in its lower portion. The driven shaft 38 is supported by the bearings 64, 66.

[0025] A third sprocket wheel 68 is connected to the driven shaft 38 outside the housing 50. The third sprocket wheel 68 transmits the power out of the power transmission device 26 via a chain 70 to another sprocket wheel (not shown) attached to the rear wheel 28. Thus, the rotational speed of the engine 24 is reduced by the timing belt transmission device 40, and then by the chain transmission between the third sprocket wheel 68 and the rear wheel 28. This provides rotational speed reduction suitable for the scooter 10.

[0026]FIGS. 5 and 6 show embodiments of the timing belt 46. In FIG. 5, the timing belt 46 is made of rubber and has teeth 72 that engage with the teeth 74 of the first and second sprocket wheels 42, 44. Alternatively, the timing belt 46 may be a chain 74 as shown in FIG. 6. The chain 76 has a plurality of links 78 that engage with the teeth 74 of the first and second sprocket wheels 42, 44.

[0027] By the above construction, a simple and reliable power transmission device for a small scooter is provided. Since the load applied on the power transmission device is distributed on the two or more timing belts and sprocket wheels, the power transmission device can absorb abrupt changes such as starting and stopping of the scooter, and impacts from the ground, etc. Since the automatic clutch handles power transmission according to the rotational speed of the engine, the scooter can be started without moving the scooter manually, and can be stopped without stopping the engine. Also, the housing enclosing the mechanism of the power transmission device protects the mechanism itself and protects the user of the scooter from injury by contacting the mechanism.

[0028] Although the invention has been described in considerable detail, other versions are possible by converting the aforementioned construction. Therefore, the scope of the invention shall not be limited by the specification specified above. The power transmission device of the present invention can be used for any small transportation means that require a simple, reliable and convenient power transmission device. 

What is claimed is:
 1. A power transmission device for a powered scooter comprising: a) a drive shaft; b) a driven shaft; and c) two or more timing belt transmission devices; wherein each of the timing belt transmission devices includes a first sprocket wheel attached on the drive shaft, a second sprocket wheel attached on the driven shaft, and a timing belt wound on the first sprocket wheel and the second sprocket wheel; wherein the ratio of the diameter of the first sprocket wheel and the diameter of the second sprocket wheel is predetermined.
 2. The power transmission device for a powered scooter of claim 1 wherein the timing belt is made of rubber and has teeth that engage with the teeth of the first and second sprocket wheels.
 3. The power transmission device for a powered scooter of claim 2 further comprising an automatic clutch connected to the drive shaft, wherein the automatic clutch transmits power of an engine of the powered scooter when the engine rotates above a predetermined rotational speed, and the automatic clutch does not transmit power of the engine when the engine rotates below a predetermined rotational speed.
 4. The power transmission device for a powered scooter of claim 2 further comprising a housing that encloses the drive shaft, the driven shaft and the timing belt transmission devices.
 5. The power transmission device for a powered scooter of claim 4 wherein the housing has recesses and bearings received in the recesses, wherein the drive shaft and the driven shaft are supported by the bearings.
 6. The power transmission device for a powered scooter of claim 1 wherein the timing belt is a chain that has a plurality of links that engage with the teeth of the first and second sprocket wheels.
 7. The power transmission device for a powered scooter of claim 6 further comprising an automatic clutch connected to the drive shaft, wherein the automatic clutch transmits power of an engine of the powered scooter when the engine rotates above a predetermined rotational speed, and the automatic clutch does not transmit power of the engine when the engine rotates below a predetermined rotational speed.
 8. The power transmission device for a powered scooter of claim 6 further comprising a housing that encloses the drive shaft, the driven shaft and the timing belt transmission devices.
 9. The power transmission device for a powered scooter of claim 8 wherein the housing has recesses and bearings received in the recesses, wherein the drive shaft and the driven shaft are supported by the bearings. 